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Old 23rd June 2008, 11:30 AM   #161
Mooly is offline Mooly  United Kingdom
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The - 3db point is at around 120 Khz for the power amp alone, and around 100 khz for the amp as a whole. This picture shows that point where the output is - 3db down. At this point there is obvious phase shift of course.
I have one confession to make now The amp is to the circuit details posted of course and on carefully designed PCB,s, however there is one difference, C2 the 150 pf cap at the input is NOT fitted. The amp is 100% stable but it seemed "prudent" to include it if anyone was going to have a go perhaps on veroboard or similar ( Space, why did I just think of you ).
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Old 23rd June 2008, 11:37 AM   #162
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And as the sun was shining (Light is everything with a 29.99 camera here is another shot of the internals, preamp along the side with FET switching done as near the inputs as possible. The board at the bottom left is a remote decoder, made from discrete logic ( pic programming is something I must get into ).
Each amp module has it's own offset protection on the PCB to the right of each "can". Note the orange earth bonding wire along the front top edge of the case.
And that's about it really.
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Old 24th June 2008, 01:54 AM   #163
KLe is offline KLe  Australia
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Hi Mooly

Where have you hidden the heatsinks ...

What size tranny are you using ...

I see that you have snubbed the Diode Bridge (single bridge only) ...

What size are the PSU caps (only 2) ...

What does the orange wire, the one at the front, do?

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Old 24th June 2008, 06:53 AM   #164
Mooly is offline Mooly  United Kingdom
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Hi Kle,
The tranny is a 300 va feeding a single bridge.
The main caps are 4700/63 volt high ripple types. There is further "local" decoupling (Around a 1000 mfd total per rail per amp) on the PCB's to the left of each can and finally 220 mfd actually on board next to the MOSFET's. To the left of the bridge and caps -- you can't see it in the picture-- is a series regulator (pre reg) that give +/-25 volts. This feeds the preamp which has local shunt regulation for all the active stages.
The case is earthed and the orange wire is an earth bonding wire to really make sure both sides of the case are at the same potential rather than relying just on cabinet screws etc.
The heatsinks !! The heatsinking capacity is actually better than it might look. The cans were from two Sony Betamax videos (SLC9) and were perfect for making amp modules in. I designed the PCB's to be an exact fit. The MOSFET's are clamped internally using the original "chopper transistor" hardware. There is a small integral heatsink at the rear, but this is helped by the fact that the "Aluminium can" is both thick and sandwiched between the heatsink and the internal plate the transistors are on. So it's all "one" big heatsink really, nice ventilation holes in it and the top plate of the case has slits in just the right place. Add then the fact it's all bolted to a metal case as well and it's all pretty good. The amp runs cool (almost cold) even after several hours, and even after say 1 hour of really serious listening it's only warm at the back, and cools back down within minutes.

No comments on the oscilloscope square wave testing anyone
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Old 24th June 2008, 09:25 AM   #165
KLe is offline KLe  Australia
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Hi Mooly

I certainly no expert, but they look really good to me.

Perhaps Andrew can provide some detailed comments.

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Old 24th June 2008, 10:36 AM   #166
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Default Hi!

Nice, but loudspikers terminals must change places!,onli internal wiring

You'l cross cables, imagine that!

Regards zeoN_Rider
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Old 24th June 2008, 01:30 PM   #167
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Hello Zeonrider,
I'm puzzled You have asked this before so I feel I am not understanding your question properly. Please can you explain. This is the plan of the listening room, same as I posted before
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Old 2nd July 2008, 02:55 AM   #168
KLe is offline KLe  Australia
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Quote:
Originally posted by space2000
hi mooly,
i am a bit confused about somethings. output having some voltage it is about 5.6v ... need comments pls.
Hi space2000

How did it all go? Is the amp up and running now?

Were you planning to give us a review of Mooly's amp?

thanks
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Old 2nd July 2008, 04:19 AM   #169
KLe is offline KLe  Australia
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Default Re: PCB for Mooly amp

Quote:
Originally posted by alex mm
Hi all ,
PCB not tested, but possible working http://i30.tinypic.com/f3gv80.jpg
regards alex mm
Hi alex mm
Same questions as the ones to space2000 ...

How did it all go? Is the amp up and running now?

Were you planning to give us a review of Mooly's amp?

thanks
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Old 2nd July 2008, 06:31 AM   #170
Mooly is offline Mooly  United Kingdom
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Not heard off Space for a while !!
You've not blown yourself up have you
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